FMO5 and COVID-19: It has been hypothesized that excessive activation of RAS system might contribute to progression of COVID-19 related lung injury by promoting inflammatory response and cytokine storm,25 stimulating the NADH/NADPH oxidase system,26 and triggering cell contraction and vasoconstriction.27 Further studies are needed to better understand the underlying biological mechanisms involved in the association between hypertension and adverse outcomes in COVID-19.